1. Field of the Invention
This invention relates to a method for manufacturing a multiple-phase particle and to an apparatus for manufacturing the multiple-phase particle.
2. Description of the Related Art
Multiple-phase particles such as microcapsules and composite fine particles are used extensively in various technical fields including biotechnology, the drug industry, the food industry, the cosmetic industry, and the paint industry, etc. When a multiple-phase particle is manufactured using lipid as an emulsifier, the product is referred to as a lipid multiple-phase particle. Further, the multiple-phase particle can be classified, according to the thickness of the membrane thereof, into a double emulsion and a vesicle (a reversed vesicle). Depending on the number of inner gas phase, aqueous phase or oil phase, the double emulsion can be classified into a multiple-phase-type emulsion and a single-phase-type emulsion.
In the DDS (Drug Delivery System) where the enhancement of pharmacological effects and the suppression of side effects are aimed at, the lipid multiple-phase particle is advantageous in that it is capable of controlling the release of medicine, improving the absorbability and enhancing the target directivity, and is also more excellent as compared with polymeric carrier in terms of toxity, antigenicity, irritation, etc. However, since the lipid multiple-phase particle is relatively instable as compared with polymeric carrier, it is difficult to supply a sufficient quantity as required of the particle immediately when immediate supply thereof is needed.
Although it is relatively easy to manufacture a multiple inner aqueous phase type emulsion, the double emulsion to be obtained lacks uniformity of particle size. Therefore, when the lipid multiple-phase particle is to be employed as a microcarrier, there will be raised the problems that it is difficult to control the dosage of chemicals as well as the rate of releasing the chemicals.
In order to manufacture a vesicle which is excellent in uniformity of particle size, it will be required to undergo a series of complicated steps such as drying of lipid, stirring, ultrasonic treatment, pressing, etc. Since the manufacturing process thereof includes the employment of harmful volatile organic substance such as chloroform, it is difficult to directly entrap a bioactive substance in the vesicle. Further, it is difficult to quickly and automatically manufacture a vesicle excellent in uniformity of particle size and to manufacture a vesicle enclosing therein a bioactive substance. It is also difficult to manufacture a vesicle where the inner membrane and the outer membrane thereof are asymmetric. Moreover, since the particle diameter of vesicle to be manufactured is as small as about 20 nm-50 nm, it is difficult to entrap a sufficient quantity, per unit volume, of a high-molecular substance such as protein, DNA, RNA, etc., so as to secure high activity thereof.